It's either sticking firing pins or the fact that after you fire you have to cock the main springs when opening the barrels. That takes extra pressure to open because it
is cocking the main springs.
J.M.

Go slow and as you take each part out, reinstall it. Then take it out again and move to the next part. If you run into trouble, you can email me at johnnymeadows55@yahoo.com. Send me your phone number and I'll call you
ASAP
Johnny Meadows